Trimethylaluminum (TMA)-Catalyzed Reaction of Alkynyllithiums with Ethylene Oxide: Increased Yields and Purity of Homopropargylic Alcohols

Abstract

An efficient protocol was developed to obtain homo­propargylic alcohols. Subjecting alkynyllithiums and ethylene ­oxide to 10-20 mol% of trimethylaluminum provided homopro­pargylic alcohols in good yields.

Key words

catalysis - homopropargylic alcohols - alkynyllithiums - nucleophilic additions - ethylene oxide - trimethylaluminum

References

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7

Without the addition of Me₃Al the yields were approximately 10% and using stoichiometric BF₃·OEt₂ gave 54% yield of a mixture of inseparable by-products.

12

The ethylene oxide was condensed in a separate two-neck pear shaped flask equipped with a coldfinger. Then, the ethylene oxide was removed with a plastic syringe that was pre-cooled by capping the needle with a large septa and placing it in a Ziploc bag, which was then placed in the freezer for 20 min prior to use. If larger amounts (>1 mL) of ethylene oxide were needed the desired amount was condensed into an addition funnel with a cooling jacket and added dropwise to the reaction.